Apparatus for water jet propulsion

ABSTRACT

Apparatus for water jet propulsion in which a screw propeller is integrally formed with a surrounding duct, which surrounding duct rotates with the screw propeller to eliminate blade-tip vortex. A duct comprised of alternately disposed movable and stationary segments, which movable elements are adjustably positioned to mate with the stationary segments to provide optionally either an intake duct with an optimum configuration to reduce cavitation or a discharge duct with an optimum configuration.

United States Patent 1 Cameron 1 Nov. 20, 1973 [54] APPARATUS FOR WATERJET 340,237 4/1886 Nagel et al..... /222 PROPULSION 1,326,730 12/1919Helguera 60/221 2,083,447 6/1937 Hoffmann.. 137/151.1 ux

[ Inventofl Donald Cameron, 2213 Roosevelt 3,044,259 7/1962 Tuttle60/222 Cahf' FOREIGN PATENTS OR APPLICATIONS 1 FlledI July 1970 220,5053 1959 Australia 239/265.39

[21] Appl. No.: 51,450

[52] US. Cl 60/221, 239/265, 239/39,

51 I t C1 B63h l il /i3 [57] ABSTRACT 1 i "60/221 Apparatus for waterjet propulsion in which a screw ll 5 l 15 f propeller is integrallyformed with a surrounding duct, 239/265 1 6 265 which surrounding ductrotates with the screw propeller to eliminate blade-tip vortex. A ductcomprised of [56] References Cmd alternately disposed movable andstationary segments, which movable elements are adjustably positioned toUNITED STATES PATENTS mate with the stationary segments to provideoption- 3,032,977 Neitzel 239/265.33 either an intake duct with anoptimum configu a- Xg y 6 59 tion to reduce cavitation or a dischargeduct with an 7 ramson... 3,011,561 12/1961 Wagener.... 60/221 ux optlmumconfigumuon' 2,701,440 2/ 1955 Reime 137/ 15.1 UX- 4 Claims, 6 DrawingFigures 191 I 4 9o 11- 1 E} w l 3 15a ;5 Q 72 3 I T l l w -2:3 //,,L,1\\\\\\\ a\\\\\\ I 74 82 I N1\ 5 I46 4655 a3 2,, I45 2 PrimaryExaminerClarence R. Gordon AttorneyJack M. Wiseman PMENTEBHHV 20 I975llll I SHEET 1 UP 4 FIG. 7

INVENTOR. DONALD L. CAMERON ATTORNEY INVENTOR DONALD CAMERON ATTORNEYPMENTEDHUVI-1U m5 sum 3 [1r 4 PATENTEH "0V 2 0 I975 SHEET U UF 4INVENTOR. DONALD L. CAMERON %J M. W

A T TOR/V5 Y 1 APPARATUS FOR WATER JET PROPULSION BACKGROUND OF THEINVENTION The present invention relates in general to apparatus forpropelling water vehicles, and more particularly, to apparatus forpropelling water vehicles by water-jet propulsion.

Heretofore, screw blades employed for propelling water vehicles wereinefficient. Such inefficiency was primarily caused by blade-tip vortexand cavitation. Blade-tip vortex is caused by water passing across thetop of fast moving blade-tips, which produces a circular vortex action.This action creates a turbulance and thereby decreases the efficiency ofthe blade-tips. Cavitation is a formation of small bubbles of watervapor resulting from a decrease of water pressure on the rear side ofthe rotating screw blades. When the water pressure is reduced to a pointequal to or below the vapor pressure of the ambient water, the watervaporizes and forms small bubbles or cavities.

Both blade-tip vortex and cavitation, and particularly cavitation,produce noise which is objectionable. This is particularly so inconnection with submarines when a quiet operation is desired.

Attempts have been made to overcome the problems arising out ofblade-tip vortex and cavitation. One arrangement has been to surroundthe blade screw with a duct fitted closely to the tips of the blades toassist in reducing blade-tip vortex. However, there appears to be a needof some clearance between the fast moving blade-tips and the stationarysurrounding metal duct. This clearance produces a leakage path whichpermits a turbulance similar to blade-tip vortex. Fluid passing througha constricted opening under great pressure and at a high velocity is tosome extent abrasive. The abrasive action wears away both the blade-tipand surrounding duct, which results in an increase in the clearance. Theincrease in clearance, in turn, increases the amount of blade-tipturbulance.

Presently existing water-jet apparatus for propelling water vehiclesemploy an intake duct or a discharge duct with a combined configurationfor the intake side and for the discharge side. The combinedconfiguration is a compromise between the optimum shape for an intakeduct and the optimum shape for a discharge duct. While such a combinedshape is more efficient than attempting to reverse the engines with aunit having an optimum shape for the intake side and an optimum shapefor the discharge side, such a unit would provide reduced power when theengines are reversed. Such a configuration, which is sometimes referredto as the English Curve, is quite inefficient and tends to lackusefulness for a water-jet propulsion system.

SUMMARY OF THE INVENTION Apparatus for propelling water vehicles bywater-jet propulsion, in which a propeller is formed with a surroundingduct fixed thereto. The surrounding duct rotates with the propeller forreducing blade-tip vortex. As a further feature, the drive shaft for thepropeller can optionally be set-off from the axis of the hub to increasethe efiective face area of the propeller.

A duct for water-jet propulsion apparatus having alternately disposedmovable and stationary segments, in which the movable segments areadjustably positioned in mating relation with the stationary segments toprovide optionally either an optimum configuration as an intake duct toreduce cavitation or an optimum configuration as a discharge duct. Anintake duct for waterjet propulsion having a frusto-conicalconfiguration to reduce cavitation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the apparatusof the present invention for propelling water vehicles by water-jetpropulsion.

FIG. 2 is a vertical section of the apparatus shown in FIG. 1 takenalong line 2 2 of FIG. 1.

FIG. 3 is an end view of the apparatus shown in FIGS. 1 and 2 takenalong the line 3-3 of FIG. I at the aft end of the apparatus.

FIG. 4 is an end view of the apparatus shown in FIGS. 1 and 2 takenalong the line 4-4 of FIG. 1 at the forward end of the apparatus.

FIG. 5 is a vertical section view taken along line 55 of FIG. 2.

FIG. 6 is a section taken along line 66 of FIG. 3.

7 DESCRIPTION OF THE PREFERRED EMBODIMENTS Illustrated in FIGS. 1-5 is atwin water jet propulsion apparatus 9 embodying the present invention,which comprises identical water jet propulsion apparatus 10 and 10a.Hence, the water jet propulsion apparatus 10 will be described in detailhereinafter and like parts for the water jet propulsion apparatus 10awill be designated by the same reference numeral but with a suffix a Thewater jet propulsion apparatus 10 (FIG. 2) comprises ducts l5 and atopposite ends thereof. Joining the confronting ends of the ducts l5 and20 is a screw propeller which is disposed within a cylindrical housing30. Rotating the screw propellers 25 and 25a is a common drivearrangement (FIGS. 4 and 5).

Either duct 15 or duct 20 can be adjustably employed as the intake ductor as the discharge duct. For purposes of convenience, in thedescription to follow the duct 15 will be described as the intake ductand the duct 20 will be described as the discharge duct.

The intake duct 15 in the preferred embodiment has a configuration of atruncated cone to reduce cavitation and comprises 16 segments. Segments50-57 are movable segments and segments -67 are stationary segments. Themovable segments 50-57 and the fixed segments 60-67 are alternatelydisposed to form the periphery wall of the duct 15. The stationarysegments are fixed at proximal ends thereof to the housing 30 (FIG. 2).The movable segments are pivotally connected at their proximal ends tothe housing 30. In the exemplary embodiment for the intake duct 15, themovable segments 50-57 are extended angularly relative to the housing 30and mate with the fixed segments 60-67 (FIG. 3) to form a relativelysmooth inner frusto-conical wall for the path of travel of wateradvancing toward the propeller screw 25, which may be referred to as theoptimum configuration of an intake duct. Thus, as an intake duct, themovable segments fan out angularly relative to the housing 30 to matewith the stationary segments.

In a like manner, the discharge duct 20 includes 16 segments. In theexemplary embodiment, the discharge duct 20 has a cylindricalconfiguration formed by eight movable segments -77, which are retractedangularly relative to the housing 30 to mate with adjacent movablesegments thereof for the discharge of water expelled by the propellerscrew 25. This configuration may be referred to as the optimumconfiguration for a discharge duct. The movable segments are pivotallyconnected to the proximal ends thereof to the housing 30 (FIG. 2) andthe stationary segments are fixed at their proximal ends to the housing30. When the movable segments are retracted angularly relative to thehousing 30, they form the inner cylindrical wall of the duct 20 for thedischarge flow of the water (FIG. 4).

Connected to the movable segments 50-57 for the duct are angularactuating arms 90-97, respectively. Each arm has one leg thereof fixedto its associated movable segment for imparting an angularly extendingor retracting movement thereto relative to the housing 30. At thejunction between the legs, the actuating arms 90-97 are pivotallyconnected for pivotal movement to the housing 30 by means of suitableears and pins. Mounted on the housing 30 are suitable hydrauliccylinders 100-107. Pistons 110-117 are disposed within the cylinders100-107, respectively, and are connected through their piston rods tothe other legs of the arms 90-97, respectively, for imparting thereto apivotal movement. Thus, imparting rectilinear movement to the pistons110-117 causes the actuating arms 90-97, respectively, to extend orretract the movable segments 50-57, respectively, of the duct 15angularly relative to the housing 30.

In a like manner, connected to the movable segments 70-77 for the ductare angular actuating arms 120-127, respectively. Each arm has one legthereof fixed to its associated movable segment for imparting anextending or retracting angular movement thereto relative to the housing30. At the junction between the legs, the actuating arms 120-127 arepivotally connected for pivotal movement to the housing 30 by means ofsuitable ears and pins. Pistons 130-137 are disposed within thecylinders 100-107, respectively, and are connected through their pistonrods to the other legs of the arms 120-127, respectively. The pistons130-137 are oppositely located in the cylinders 100-107, respectively,with respect to the pistons 110-117. Intermediate the pistons 130-137and pistons 110-117 are sealing plugs 140-147, respectively.

For actuating the pistons 110-117 and the pistons 130-137 within thecylinders 100-107 to impart a reciprocating movement thereto, fluidunder pressure is supplied to each side of the hydraulic cylinders100-107. Toward this end, a network of hydraulic supply conduits 140 anda network of hydraulic return conduits 145 supply positive fluidpressure to each end of each side of the cylinders 100-107. A suitablesource of fluid under pressure, not shown, is connected to the network140 and 145. The hydraulic supply conduits 140 are connected to thelowest pressure point in each side of the hydraulic 100-107 and thehydraulic return conduits 145 are connected to the highest pressurepoint in each side of the hydraulic cylinders 100-107, whereby positivefluid pressure is alternately applied to each end of each side of thehydraulic cylinders 100-107 while the return network is opened to permitfluid on the other end of each side of the hydraulic cylinders 100-107to be evacuated. An automatic bleed arrangement is provided, since anyentraped air will rise and will be entraped to be carried out with thefluid in its exhaust cycle. Conventional 0- rings 146 are provided asfluid seals for the hydraulic system.

For limiting the angular extent of movement of the movable segments50-57 for the duct 15 so as to enable the movable segments 50-57 and thefixed segments 60-67 to mate properly in the intake adjusted position orthe discharge adjusted position, adjustment screws 150-157 are mountedon the arms -97, respectively. The screws 150-157 adjustably engage thehousing 30 to limit the angular extent of travel of the associatedactuater arm and permit adjustment thereof for proper mating of themovable segments 50-57 with the fixed segments 60-61. Adjustment screws160-167 on the cylinders -107, respectively, limit the linear extent oftravel of the pistons -117, respectively, and permit adjustment thereoffor proper mating of the movable segments 50-57 in the discharge modefor the duct 15.

Similarly, adjustment screws similar to adjustment screw 170 for theactuating arm are adjustably mounted on the actuating arms 121-127,respectively, for engagement with the housing 30 to limit the angularextent of the movable segments 70-77 for the duct 20 so as to enable themovable segments 70-77 to properly mate in the intake adjusted positionor the discharge adjusted position with the stationary segments 80-87.The adjustment screws, which are similar to the adjustment screws -157previously described, limit the movement of the movable segments 70-77by restricting the angular extent of the pivotal movement of theactuating arms 120-127 toward the housing 30. Adjustment screws, notshown, on the cylinders 100-107, respectively, similar to the adjustmentscrews -167, limit the linear extent of the travel of the pistons130-137, respectively, and permit adjustment thereof for proper matingof the movable segments 70-77 in the discharge mode of the duct 20.

From the foregoing, it is to be observed that the duct 15 is selectivelyformed into the shape of a truncated cone and functions in this mode asthe intake duct. Water enters the wide end of the duct 15 and impingeson the sloping inner walls of the duct 15. This action creates apressure head which is converted into a velocity head as the wateradvances toward the screw propeller 25. The duct 15 gradually decreasesin crosssectional areas in the downstream direction. As the waterproceeds through the screw propeller 25, it is accelerated anddischarged through the cylindrical shape which is the exemplaryconfiguration for a discharge duct.

Disposed within the housing 30 in the path of travel of water advancingthrough the duct 15 is the screw propeller 25. The screw propeller 25comprises a hub which extends in the direction of travel of the waterfrom the duct 15 toward the duct 20. Fixed to the hub or core 180 arescrew blades 181-185. As is wellknown, the hub 180 rotates fitted withradiating blades 181-185, which are arranged in a spiral configuration.The hub 180 is smaller than the inner core of conventional or shaftdriven screw propellers.

According to the present invention, a cylindrical tube, sleeve, duct orcollar is fixed to the distal ends of the screw blades 181-185 forrotation therewith. The duct 190 may be integrally formed with thedistal ends of the blades 181-185 or welded thereto. Suitable bearings,such as roller bearings 191, are disposed between the rotating duct 190and the housing 30, which serve as thrust bearings as well asantifriction bearings.

integrally formed with the duct 190 is a driven gear 195 for impartingrotation to the screw propeller 25 and the surrounding duct 190. Meshingwith the gears 195 and 195a is a centrally located drive gear 196 (FIG.5), which is keyed to a drive shaft 197 of the vehicle. O-rings 198 sealoff the gear box to reduce the seepage of water thereinto and to reducethe escape of gear lubricant into the water.

By virtue of the duct 190 being fixed to the distal ends of the screwblades 181-185 for rotation therewith and by eliminating clearancebetween the tip of the screw blades and the duct surrounding the screwpropeller, blade-tip turbulance is substantially eliminated.

The cavitation is substantially reduced by increasing the pressure onthe back side of the screw blades 181-185, which is achieved by theacceleration of intake water in the frusto-conically shaped intake ductof the present invention.

1 claim:

1. A duct for fluid jet propulsion apparatus comprising:

a housing;

a plurality of movable segments pivotally connected to said housing;

a plurality of stationary segments fixed to said houssaid movablesegments and said stationary segments being alternately disposed and inadjacent relation about said housing; and

means connected to said movable segments for pivoting said movablesegments relative to said housing into selective mated positions withadjacent segments for at times forming a desired configuration as anintake duct and at other times forming a desired configuration as adischarge duct,

said movable segments fan out pivotally from said housing into angularexpansion for mating relation with said stationary segments to form adesired configuration as an intake duct.

2. A duct as claimed in claim 1 wherein said movable segments areretracted angularly with respect to said housing for mating relationwith adjacent movable segments to form a desired configuration as adischarge duct.

3. A duct as claimed in claim 2 wherein said means includes an hydraulicsystem.

4. A duct as claimed in claim 3 and comprising adjustment means forrestricting the extent of movement of said movable segments.

1. A duct for fluid jet propulsion apparatus comprising: a housing; aplurality of Movable segments pivotally connected to said housing; aplurality of stationary segments fixed to said housing; said movablesegments and said stationary segments being alternately disposed and inadjacent relation about said housing; and means connected to saidmovable segments for pivoting said movable segments relative to saidhousing into selective mated positions with adjacent segments for attimes forming a desired configuration as an intake duct and at othertimes forming a desired configuration as a discharge duct, said movablesegments fan out pivotally from said housing into angular expansion formating relation with said stationary segments to form a desiredconfiguration as an intake duct.
 2. A duct as claimed in claim 1 whereinsaid movable segments are retracted angularly with respect to saidhousing for mating relation with adjacent movable segments to form adesired configuration as a discharge duct.
 3. A duct as claimed in claim2 wherein said means includes an hydraulic system.
 4. A duct as claimedin claim 3 and comprising adjustment means for restricting the extent ofmovement of said movable segments.